https://leetcode-cn.com/problems/remove-linked-list-elements/
https://github.com/P2P-Learning/P2P_Learning/issues/17#issuecomment-603020930
func removeElements(head *ListNode, val int) *ListNode {
	if head == nil {
		return nil
	}
	// 给链表扩展一个虚拟头节点
	dummy := &ListNode{Next: head}
	// 遍历链表,判断下一个节点是否是被删除节点
	cur := dummy
	for cur.Next != nil {
		if cur.Next.Val == val {
			cur.Next = cur.Next.Next
		} else {
			cur = cur.Next
		}
	}
	return dummy.Next
}
82. 删除排序链表中的重复元素 II
21. 合并两个有序链表
原文:https://www.cnblogs.com/yudidi/p/12558414.html